Hpyerlipidemia may accelerate atherogenesis in the diabetic and is associated with increased cardiovascualar morbidity and mortality. Patients with diabetes mellitus have a variety of hyperlipoproteinemias. Sterol balance studies suggest that the hyperglycemia and/or "diabetic control" may influence sterol synthesis and excretion differently in maturity onset diabetes mellitus (onset at 30 years of age or older) with normal serum lipids (10 patients), type IV hperlipoproteinemia (10 patients), type IIa hyperlipoproteinemia (10 patients) will be admitted to the clinical Research Center for sterol balance and cholesterol absorption studies. Similarly, 30 non-diabetic patients with normal serum lipids (10 patients), with type IV hyperlipoproteinemia (10 patients), type IIa hyperlipoproteinemia (10 patients) will be studied in the Clinical Research Center. Differences in sterol balance data and in cholesterol absorption in the diabetic and non-diabetic patient with and without hyperlipidemia and the relationship of these differences to diet, hyperglycemia, lipid levels, insulin and glucagon levels, and insulin treatment will be evaluated. This investigation will identify by sterol balance studies differences in the mechanisms for hyperlipidemia in the diabetic and nondiabetic patient. Such information will have significance in the management of the diabetic patient with and without hperlipidemia. Such data will provide the basis for guidelines for improved treatment of the diabetic patient by measures involving the antidiabetic and/or anti-lipid therapy so as to reduce lipid production and hyperlipidemia and ultimately, reduce the risk to accelerated atherogenesis.